# Paid Search Acquisition Economics for Local Businesses > Work out what a booked job really costs from Google Ads, using plain definitions of CPA, ROAS, and contribution margin and a worked example. Canonical: https://vassalmarketing.com/information/paid-search/paid-search-acquisition-economics/ **Maintained by Vassal Marketing** · Last updated on September 26, 2026 Reviewed at least quarterly and whenever a platform or rule it cites changes. General information, not legal or professional advice. Check rules that affect your business with a qualified professional. Add up everything you paid—ads plus management—and divide by the jobs you actually booked, not by Google's conversion count. Compare that with what an average job leaves after labor and materials. If each job still leaves money after ad costs, the campaign is paying its way. ## Why this matters Three terms come up constantly. CPA (cost per acquisition) in Google Ads is ad spend divided by recorded conversions—often form fills and calls, not booked jobs. ROAS (return on ad spend) is the conversion value you've told Google about divided by ad spend; it's only as real as that value. Contribution margin is what a job leaves after the costs of doing it, such as labor and materials, before overhead. The SBA uses the same idea in its break-even guidance. Hypothetical example: $1,500 in ad spend plus $500 in management is $2,000. That month brings 40 calls and forms, of which 30 are real inquiries, 12 are qualified, and 6 become booked jobs. Google Ads might show a CPA of about $38 ($1,500 ÷ 40). Your cost per booked job is about $333 ($2,000 ÷ 6). If an average job leaves $600 after labor and materials, each job contributes about $267 after ad costs. ## Responsible practices ### Start with what a job leaves behind For each promoted service, write down the average price collected and the costs that rise with each job—labor, materials, commissions. The difference is contribution margin. Keep it separate from overhead, taxes, and net profit, and ask your accountant to confirm the split. ### Set the most you'll pay for a job From that margin, decide the most you're willing to spend to win one booked job—your allowable acquisition cost. Divide by your close rate to get a rough ceiling per qualified lead. Treat these as planning limits, not forecasts. ### Group leads from the same month Keep a month's clicks, inquiries, labels, booked jobs, and revenue together. Don't mix new leads with ones that closed months ago, or different services with different margins, in one ratio. ### Use the full cost Add management fees and campaign-specific tools—call tracking, landing pages, software—to Google ad spend. Show ad-only and fully loaded costs side by side. Allocate shared costs the same way every month. ### Treat Google's values with care Google lets you set conversion values and import later outcomes. A form, qualified lead, booked job, invoice, and payment are different events. Note what each value means and whether it's real or estimated. Don't call an estimate revenue. ### Wait before judging Decide how long to wait before judging a month—long enough for leads to be quoted, booked, and paid. Google notes that conversion delay makes recent CPA look higher and ROAS lower. Mark unfinished months and decide to keep, test, narrow, or pause from finished ones. ## Acquisition economics worksheet checklist 1. Write down the average collected price and job costs for each promoted service. 2. Calculate the contribution margin per job. 3. Set the most you'll pay to win one booked job. 4. Add up ad spend, management, and campaign tools for the month. 5. Count real inquiries, qualified leads, and booked jobs from that month's leads. 6. Divide full cost by booked jobs once enough time has passed to judge. 7. Record the decision—keep, test, narrow, or pause—and the next review date. ## Avoid these failures - Treating revenue, Google conversion value, or ROAS as profit - Reporting ad spend alone as the cost per customer while leaving out management and tools - Dividing spend by every form and call instead of qualified leads and booked jobs - Judging a month before its leads have had time to book and pay - Assuming an optimistic close rate or last quarter's result will repeat ## Questions business owners ask ### What is the difference between CPA and cost per booked job? CPA in Google Ads is ad spend divided by recorded conversions, which are often calls and forms. Cost per booked job divides your full cost—ads plus management and tools—by jobs you actually booked. In the hypothetical example above, CPA is about $38 while cost per booked job is about $333. ### Should we use revenue or contribution margin? Contribution margin. Revenue hides the labor and materials needed to do the job. Subtract those to see what each job leaves, and keep overhead and taxes separate. Your accountant can confirm which costs belong where. ### Can Google Ads conversion value or ROAS be used as profit? Not unless you've set it up that way. The value may be a fixed estimate, an imported amount, or a guess. Note where it comes from and compare it with your records before calling it revenue or profit. ### How soon can we judge the numbers? Once most of a month's leads have been quoted, booked, or closed out. That might be a few weeks for quick jobs or several months for larger projects. Recent months will look worse in Google Ads because conversions arrive late. ## Primary guidance - [U.S. Small Business Administration: Break-even point](https://www.sba.gov/business-guide/plan-your-business/calculate-your-startup-costs/break-even-point) - [Google Ads: Set conversion values](https://support.google.com/google-ads/answer/7197048?hl=en) - [Google Ads: About offline conversion imports](https://support.google.com/google-ads/answer/2998031?hl=en) - [Google Ads: About conversion lag reporting](https://support.google.com/google-ads/answer/9347141?hl=en) ## Connected guidance - [Google Ads waste prevention](https://vassalmarketing.com/information/paid-search/google-ads-waste-prevention.md): Separate avoidable spend from learning cost before judging the math. - [Paid search lead quality](https://vassalmarketing.com/information/paid-search/paid-search-lead-quality.md): Count qualified leads and booked jobs consistently so the math uses real outcomes. - [Google Ads spend vs. management fees](https://vassalmarketing.com/information/paid-search/google-ads-spend-vs-management-fees.md): Add up ad spend, management, and tools before calculating full cost. Auctions, traffic, conversions, lead quality, acquisition cost, booked work, margin, and revenue are not guaranteed.